Drive with segmented inverter housing

This application is the U.S. National Stage of International Application No. PCT/EP2020/080958, filed Nov. 4, 2020, which designated the United States and has been published as International Publication No. WO 2021/099121 A1 and which claims the priority of European Patent Application, Serial No. 19210995.7, filed Nov. 22, 2019, pursuant to 35 U.S.C. 119 (a)-(d).

The invention relates to an electronic add-on part, a drive unit with a dynamoelectric machine and at least one electronic add-on part as well as the production of the electronic add-on part.

A drive system with variable rotational speeds comprises a motor and an inverter which form a common unit.

Such drive units are known, for example, from DE 198 12 729 A1. An electric motor is described there, in particular with a fan propeller to form an axial or radial fan, with a drive unit and a control unit having a control housing, wherein the drive unit has a stator, a rotor and at least one electric coil and wherein the control unit has an electronic circuit for controlling or regulating the current supply to the coil. The drive unit and the control unit are formed by modules, and contact elements assigned to one another are provided for mutual electrical connection.

Likewise, a drive unit is known from DE 38 42 588 A1. A collector-free direct current external rotor motor is described there, comprising a stator which is attached to a motor flange with stator windings, an external rotor which surrounds the stator on its side facing away from the motor flange, and an electronic circuit arrangement which controls the stator windings. This circuit arrangement has a printed circuit board which is arranged on the flange side facing toward the stator and has electronic components, as well as a plurality of power semiconductors which are electrically connected to the printed circuit board and are arranged in thermally conductive contact with the motor flange. The power semiconductors are indirectly connected in a thermally conductive manner to the motor flange via a heat sink in the form of an annular disk. The heat sink forms a pre-assembled assembly with the printed circuit board and a support element holding the printed circuit board.

The production of these drive systems, consisting of a motor and an inverter, includes inter alia, the populating of a printed circuit board with power electronics, as well as their placement and the placement of further power electronics in an aluminum cast housing. The circuit board does not provide sufficient installation space to mount the complete power electronics thereon. Therefore, the power electronics must be partially mounted on the inside of the cast housing.

The cast housing functions inter alia as a heat sink. In order to ensure good heat dissipation from the cast housing, a corresponding flatness, surface roughness and thermal connection to the respective power electronics must be provided. Due to the die casting process, however, reworking is required here to ensure the required dimensions, shape tolerances and surface roughness as these cannot be guaranteed by cavities or shrinkage during cooling. Furthermore, many threaded bores are required for fastening the covers, the circuit board, the cable inlet, and the power electronics. Some of these threaded bores lead to comparatively complex processing as they are located on the inside of the cast housing and thus form an undercut.

This also leads to complex and confusing cable laying within the cast housing, which also results in a high level of manual effort in a very confined space.

Automated production and automated testing, in particular of the service components, is thus virtually impossible.

Based on this, the object of the invention is to provide a compact electronic add-on part and a compact drive unit which ensures sufficient cooling of the drive unit and can be produced with little effort.

The object set is achieved by the production of an electronic add-on part of a drive with actuator and/or inverter components by means of the following steps:

These production steps can be carried out at least partially in succession and/or at the same time.

The object is also achieved by an electronic add-on part with actuator or inverter components which are arranged on circuit boards, the circuit boards being arranged in a star-shaped manner, a central circuit board and peripheral boards surrounding it having peripheral boards which are electrically conductively connected at least to that of the central circuit board,

The object set is also achieved by means of a drive with

The entire circuit board according to the invention is composed of a plurality of, in particular, continuous partial boards, in particular a central circuit board and its peripheral boards. The peripheral boards are connected to the central circuit board via a flexible, electrically conductive construction, in particular rigid-flex connections. After the central and individual peripheral boards have been populated, these connections can be bent by a defined angle at the predetermined points. This bending process can also be carried out without tools.

Thus, the complete power electronics can be mounted on the individual circuit boards in one populating process. It is therefore not necessary to manually mount further power electronics in a housing. By using the rigid-flex connection, the available installation space in the housing can be put to optimum use.

According to the invention, the housing arrangement of the electronic add-on part is no longer designed as a cast housing. It is divided into a plurality of preferably similar segments which can be produced by means of extrusion processes.

The segments are made of a material with comparatively high thermal conductivity, such as aluminum or an aluminum alloy.

This results in a cost advantage due to the elimination of the expensive die casting mold as opposed to the extrusion die.

In contrast to a cast housing, the dimensional accuracy, the flatness, and the surface roughness of the extruded profile do not require any further processing. Furthermore, the production of the fastening bores for the peripheral boards can be realized more easily as there is no undercut in this design. The bores for fastening a lid are integrated into the extrusion die and therefore no longer have to be drilled. The extruded profile also has better thermal conductivity in contrast to the die-cast housing as the latter has a more uniform and cavity-free structure.

The degree of automation for the production of the electronic add-on part and thus of the drive is significantly increased as a result. The populating of the entire circuit board, which is composed of the central circuit board and the peripheral boards with the respective power electronics, can be carried out in a fully automated manner. The subsequent testing of the entire circuit board can also take place in a fully automated manner as this is advantageously carried out in one plane.

The power electronics of the actuator and/or inverters, and the electrical and electronic components in the electronic add-on part are understood to mean the electronics necessary for a drive or a dynamoelectric machine, which can have one or more of the components listed by way of example. Driver electronics with power supply, monitoring modules for voltage, current or thermal state, power semiconductors (IGBT, triacs, thyristors, etc.), integrated protective functions (overcurrent, undervoltage, short circuit, etc.), brake chopper, etc.

The power electronics provided on the circuit boards are contacted, for example, via a plug connection, soldered connections, etc. These power electronics are firmly connected to the associated segment or segments before, after or during contact with the peripheral board. This connection has good thermal conductivity, which is supported by the choice of materials, as well as by possible thermal compounds.

By bending or buckling the peripheral boards relative to the central circuit board, preferably by 90°, the individual segments can now be connected by means of connectors. Thus, a closed circumferential surface—the cover—is created. The peripheral boards, which are arranged essentially tangentially, are located on the inside of the cover. At least one side of the peripheral boards is electrically connected to the central circuit board. The central circuit board is essentially perpendicular to an axis of the drive.

In connection with an upper and lower lid and the cover, a closed housing arrangement of the electronic add-on part is created. Due to the electrically conductive connection between the central circuit board and the peripheral boards, no further routing of cables is required in the interior of the housing arrangement.

As a result of the use of a central and peripheral board, the complete power electronics can be populated and tested in an automated manner on the respective circuit boards. This leads to higher productivity and a significant reduction in assembly costs.

No further processing steps are required on the cover or on the segments to achieve the required dimensional accuracy, flatness, and surface roughness as these can be produced by means of extrusion methods.

The cover or the segments are made of a material with comparatively high thermal conductivity, such as aluminum or an aluminum alloy.

In this way, simpler and more cost-effective production, inter alia of the thermal connection of the power electronics to the segment, is implemented. Only the threaded bores for fastening the power electronics and the cable guide must still be produced. The bores for fastening the covers are already integrated into the extruded profile.

Furthermore, each individual segment has better coding properties through the use of the extrusion manufacturing process as opposed to a die casting process. Moreover, the expensive die casting mold can be replaced by a considerably more favorable extrusion die.

This results in a very compact and efficient drive, the components of which, in particular the electronic add-on part as well as the dynamoelectric rotary machine, can be sufficiently cooled.

Via the cover of the electronic add-on part, its elements, such as power semiconductors, control and regulating units, are cooled. In the case of the dynamoelectric rotary machine, the stator and the rotor are cooled in particular via a shaft and the cooling air flow guided along a housing of the dynamoelectric rotary machine.

The entire cover formed by segments is essentially tubular. The housing of the electronic add-on part is created by lids to be attached on both sides. Depending on the drive system, the lids have central openings—just like the central circuit board. These axial openings are sealed to the shaft by a tube in a contactless manner. Through these openings, the shaft, which inter alia is the drive shaft of the cooling unit, in particular of a fan, now projects in a contactless manner. Thus, for example, suitable self-ventilation of the drive is now possible.

The cover or the segments have axial and radially extending ribs on their outer side. The inside of the segments is preferably designed to be fiat in order to connect actuator or inverter components directly to the inside of the segment in a thermally effective manner.

The rotor of a dynamoelectric machine is also cooled, inter alia, via the shaft. Moreover, heat from the rotor is also emitted to the interior of the dynamoelectric rotary machine so that the bearing shields, bearings, and housing may likewise heat up as a result. This heat input is discharged through the air flowing around the housing and the bearing shields, in particular through the adaptable cooling unit, for example, the fan.

The stator also generates heat which, inter alia, heats up the interior of the dynamoelectric rotary machine. This heat input is likewise discharged through the air flowing around the housing and the bearing shields. Furthermore, the stator is preferably shrunk into a jacket of the housing in order to obtain a comparatively good heat transfer from the laminated core of the stator to the housing and the housing ribs.

During operation of the dynamoelectric rotary machine, the cooling unit, which is designed in particular as an internal fan, generates a cooling air flow which is first guided radially along the housing of the electronic add-on part. A fan cowl, which extends axially in the direction of the AS bearing, also guides the cooling air flow along the cooling fins of the cover and housing of the dynamoelectric rotary machine.

shows, In a basic longitudinal section, a drivewith a dynamoelectric rotary machinewhich has a statorwith a laminated core. A winding system which forms winding headson the end faces of the laminated coreof the statoris arranged in the laminated coreof the stator, facing an air gap. Non-rotatably connected to a shaftis a laminated coreof a rotor, which laminated coreinteracts electromagnetically with an energized winding system of the statorand thus leads to a rotation of the shaftabout an axis. The shaftis held in two bearings, an AS bearingand a BS bearing.

The dynamoelectric rotary machineis surrounded by a housingwhich is bounded at the end faces by bearing shields. An electronic add-on partwhich contains at least elements of an inverter and/or an actuator is located at an axial distance from the BS bearing side. The electronic add-on partis stationary and is not connected to the shaft in a rotationally fixed manner. Axially adjoining this is a fanwhich in turn is connected in a rotationally fixed manner to the shaftand generates a cooling air flow which is guided through a fan cowl. The air flow is supplied to the fanvia a suction opening.

In the case of the drive, heat build-up occurs during operation of the drive, in particular between the electronic add-on partand the facing bearing plate. Heat input takes place from both axial sides. Thus, heat loss from the inverter and/or actuator, that is to say the electronic add-on part, as well as heat from the machineleads via the bearing plate to this heat build-up between the individual components. The heat from the machineis composed, inter alia, of the heat loss from the statorand the rotor. These also heat the adjacent bearings,, which impairs the lubricant of the bearings and would require shorter lubrication intervals.

The heat is also transported via the shaft, in particular from the rotorof the dynamoelectric rotary machine, and supplied to the fanwhich functions, inter alia, as a heat output element. During operation of the dynamoelectric rotary machine, the fanalso generates a cooling air flow.

The electronic add-on partis spaced apart from the shaftand fixed in a stationary manner via mechanical connections to the adjacent bearing plate and/or to a fan cowl.

Electrical connections and/or data lines between the electronic add-on partand the dynamoelectric machineare possible via the lidand an opening in the opposite bearing plate.

Lines can likewise be guided via a connection elementinto a terminal boxof the dynamoelectric machine.

These connections are all made in compliance with the respective predetermined degree of protection via the bearing plateand/or the housingand/or a terminal boxon the housing.

shows an exemplary arrangement of an entire circuit board with a central circuit boardand peripheral boardsin one plane. A number of power modules which are electrically contacted via rigid-flex connections in the bending sectionsto the power modules arranged on the peripheral boardsare arranged on the central circuit board. In this example, the central circuit boardhas a hexagonal basic shape, one side being free of the peripheral boardin order to enable connection options there, for example to a motor and/or terminal box. Other basic shapes are also possible for the central circuit board, such as triangular, rectangular, octagonal, or dodecagonal.

The bending lines of the bending sectionsrun parallel to the respective outer edge of the selected basic shape.

Of course, oblique bending lines are also conceivable, this depends inter alia on the basic shape selected and the angle thereof.

shows the bent peripheral boardsand their thermal contact with the respective segments. The peripheral boardsare bent at a predetermined angle, in particular 90 degrees, with respect to the central circuit boardon the bending section.

The peripheral boardsare thermally connected as directly as possible to the segments.